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We used radiocarbon dating of the organic soil surface remaining post-fire to examine whether the fire burned into ancient and likely irreplaceable soil C pools. Suprisingly, it did not; all radiocarbon dates from burned soil surfaces contained bomb carbon, setting the maximum age of the burned soil surfaces at ~50 years.

This file contains the soil profile data for burned and unburned moist acidic tundra sites used to estimate C and N loss from the Anaktuvuk River Fire (2007). These sites were sampled in summer of 2008. Unburned sites were used to develop a method for estimating soil organic layer depth and plant biomass, and for determining the characteristics of unburned soil organic layers. In burned sites, we characterized residual organic soils and used biometric measurements of tussocks to reconstruct pre-fire soil organic layer depth.

Estimated mean pre-fire C and N pools, and C and N loss from 20 sites in the Anaktuvuk River Fire (2007). These sites were sampled in summer of 2008. In each site, we characterized residual organic soils and used biometric relationships developed in unburned sites to reconstruct pre-fire soil organic layer depth, and plant and soil C and N pools. We then estimated fire-driven losses of C and N from plant and soil organic layer pools.

Daily landscape-level snow cover percent data from Toolik Lake Field Station (TFS), Imnavait (IMVT), and the Sagavanirktok River DOT site (SDOT), in the northern foothills of the Brooks Range, Alaska. Data collected from May to early June 2011 to 2014.

Soil samples were collected from control, and N+P plots from within a set of treatments in Arctic LTER Moist Acidic Tundra plots established in 1989 and in 2006 . At the time of sampling the soil was separated into organic horizon, organic/mineral interface, and the upper 5cm of the mineral soil. In the lab the potential activities of seven hydrolytic enzymes was determined using fluorometric techniques (Saiya-Cork et al. 2002) modified following Steinweg et al(.2012).

The data set describes soil ergosterol concentration, which is unique to fungal membranes., from samples from Abisko, Sweden. The samples from Abisko, Sweden, were collected by E.A. Hobbie at a birch forest site and a tundra site. The Abisko sites are described in www.abacus-ipy.org/fieldsites/abisko.html.

The data set includes 15N and 13C for plant litter, soil, plants and fungal fruiting bodies (mycorrhizae), percent C (soil organic matter and percent N from samples collected in three separate trips (1990, 2004, 2007) along the transect of the Dalton Highway (AK) extending from the Yukon River on the south to Prudhoe Bay on the north.

The data set describes soil ergosterol concentration, which is unique to fungal membranes., from an Alaska transect . The soil samples from Alaska were collected in a trip from north to south along the Dalton Highway. north of the Yukon River.

The original focus of this study was an analysis of proteolytic enzyme activity of Alaskan arctic tundra soils, however initial results raised questions regarding the method (Watanabe and Hayano, 1995). Thus, the goals of the study changed to 1) an investigation of the method, and 2) a comparison of enzyme activities of two different soil layers from the arctic tundra.

Data were collected to investigate if formation of gully thermokarst (TK) results in lowering of the water table and more rapid evacuation of water from above the frost table. Data were collected from 24 shallow screened wells. 2 replicate rows of 4 wells were located at: (a) a hillslope (HS) ~120m away from the gully TK, (b) perpendicular to the gully TK (TK) and (c) perpendicular to an unimpacted water track (WT) upstream of the gully TK. Note that water levels are the distance below the ground surface and may have organic/peat layers of different thicknesses.

The (ARCSSTK) did extensive research during 2009-2011 field seasons in Arctic Alaska. The objective of this data set was to measure the quantity and biodegradability of DOC from headwater streams and rivers across three geographic regions and across four natural ‘treatments’ (reference; thermokarst-; burned-, and thermokarst + burned-impacted streams) to evaluate which factors most strongly influence DOC quantity and biodegradablity at a watershed scale.

The (ARCSSTK) did extensive research during 2009-2011 field seasons in Arctic Alaska. The objective of this data set was to measure the quantity and biodegradability of DOC from headwater streams and rivers across three geographic regions and across four natural ‘treatments’ (reference; thermokarst-; burned-, and thermokarst + burned-impacted streams) to evaluate which factors most strongly influence DOC quantity and biodegradablity at a watershed scale. This table provides physical site characteristics for the locations sampled for stream water biodegradability.

Soil temperature from three locations on the eastern side of the Toolik River where by snow fences were established as part of IPY. This is a study of how soil temperatures at 10 cm and soil moisture change across the summer at our IPY snow fence site .

The Changing Seasonality of Arctic Stream Systems (CSASN) was active from 2010 to 2012. The CSASN goal was to quantify the relative influences of through flow, lateral inputs, and hyporheic regeneration on the seasonal fluxes C, N, and P in an arctic river network, and to determine how these influences might shift under seasonal conditions that are likely to be substantially different in the future. Point transects were done throughout the sampling season to determine different substrate and cover types on the stream bottom.

A spectrophotometer was used to scan the canopy vegetation at four sites near Imnavait Creek each year from 2008 - 2010 by Toolik Lake LTER, Alaska. Reflectance spectra from 310-1130 nm are presented here with information relating the date and site of the scan.

A spectrophotometer was used to scan the canopy vegetation at four sites along Imnavait Creek in the Kuparuk Watershed near Toolik Lake LTER, Alaska. The resulting reflectance spectra were used to calculate average vegetation indices for each site and collection day.

A spectrophotometer was used to scan the canopy vegetation of ITEX harvest plots. The resulting reflectance spectra were used to calculate several vegetation indices of interest (NDVI, EVI, EVI2, PRI, WBI, Chlorophyll Index). Average values of these vegetation indices for each ITEX harvest plot are presented here. These plots also had biomass harvests performed and were analyzed for leaf area and nitrogen content (see 2003-2009gsharvest.csv, 2003-2009gsharvestLAI-N.csv).

The Anaktuvuk River Fire occurred in 2007 on the North Slope of Alaska. In 2008, three eddy covariance towers were established at sites represent ing unburned tundra, moderately burned tundra, and severely burned tundra. Several times during the 2008-2014 growing seasons, thaw depth was measured at approximately 70 points near each of these towers . Data presented here are the individual measurements for each site and date.

Inorganic Nitrogen and phosphorus were analyzed on snow samples taken from two snow pits near the long-term acrtic LTER mesic acidic tussock experimental plots. The snow layers in each pit were described and sampled separtely with the help of Matthrew Sturm.

Decadal file describing the physical lake parameters recorded at various lakes near Toolik Research Station during summers from 1983 to 1989. Depth profiles at the sites of physical measures were collected in situ. Values measured included temperature, conductivity, pH, dissolved oxygen, Chlorophyll A, Secchi disk depth and PAR. Note that some sample depths also have additional parameters measured and available in separate files for water chemistry and primary production.

Decadal file describing the physical/chemical values recorded at various lakes near Toolik Research Station during summers from 2000 to 2009. Sample site descriptors include site, date, time, depth. Depth profiles of physical measures collected in situ with Hydrolab Datasonde in the field include temperature, conductivity, pH, dissolved oxygen in both percent saturation and mg/l, SCUFA chlorophyll-a values in both volts and µg/l, and PAR.

Decadal file describing the physical/chemical values recorded at various lakes near Toolik Research Station during summers from 1990 to 1999. Sample site descriptors include site, date, time, depth. Depth profiles of physical measures collected in situ with Hydrolab Datasonde in the field include temperature, conductivity, pH, dissolved oxygen in both percent saturation and mg/l, SCUFA chlorophyll-a values in both volts and µg/l, and PAR.

Decadal file describing the chlorophyll a and primary production in various lakes near Toolik Research Station (68 38'N, 149 36'W) during summers from 1983 to 1989. Sample site descriptors include an assigned number (sortchem), site, date of analysis (incubation), time, depth and rates of primary production. The amount of chlorophyll a and pheophytin were also measured.

Decadal file describing the physical/chemical values recorded at various lakes near Toolik Research Station. Sample site descriptors include site, date, time, depth. Depth profiles of physical measures collected in situ with Hydrolab Datasonde in the field include temperature, conductivity, pH, dissolved oxygen in both percent saturation and mg/l, SCUFA chlorophyll-a values in both volts and µg/l, and PAR.

Decadal file describing the chlorophyll a and primary production in various lakes near Toolik Research Station (68 38'N, 149 36'W) during summers from 2010 to 2014. Sample site descriptors include an assigned number (sortchem), site, date of analysis (incubation), time, depth and rates of primary production. The amount of chlorophyll a and pheophytin were also measured.

Decadal file describing the chlorophyll a and primary production in various lakes near Toolik Research Station (68 38'N, 149 36'W) during summers from 1990 to 1999. Sample site descriptors include an assigned number (sortchem), site, date of analysis (incubation), time, depth and rates of primary production. The amount of chlorophyll a and pheophytin were also measured.

Thaw depth was measured using a steel probe in the Imnavait Creek watershed, near Toolik Lake, Alaska. The thaw grid includes measurements made from the valley bottom (on both sides of the stream), up the hillslope to the hilltop (watershed boundary). The thaw grid is near Imnavait water tracks 7 and 8, and measurements have been made from the 2003 season until present. Two surveys are conducted each summer, on 2 July and on 11 August (plus or minus 1-2 days on either side of those dates).

Starting in 1990 thaw depth has been measured in a small watershed of tussock tundra every July 2nd and August 11th. The UTM stake grid (stakes are in a grid at every 100 meters) was used to locate the points . All measured depths are in cm. Measurements are made within a 20 cm radius of each location point. All the measurements are then averaged into a single value for the day.

The Anaktuvuk River Fire occurred in 2007 on the North Slope of Alaska. In 2008, three eddy covariance towers were established at sites representing unburned tundra, moderately burned tundra, and severely burned tundra. Eriophorum vaginatum flowers were counted from annual photographs of each site during peak flowering season (6/17-7/20).

This material is based upon work supported by the National Science Foundation under Grants #DEB-1637459, 1026843, 9810222, 9211775, 8702328; #OPP-9911278, 9911681, 9732281, 9615411, 9615563, 9615942, 9615949, 9400722, 9415411, 9318529; #BSR 9019055, 8806635, 8507493. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.